Tube machine



Oct. 19 1926. 1,603,325 v E. E. DAVIDSON ET AL TUBE MACHINE -Fled Sept. 19. 1924 HIIIIIIIII l Pefemed oei.. l19, 1926.

.j UNITED STATES PATENToFFicE-Q ELIAS E. DAVIDSON .AND FLOBENZ P. HARTUNG, OF AKRON,- OHIO, 4ASSIG'FIOIEC'S '.l'.'0V THE B. F. GOODRIOH COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

'TUBnmcnnm Application mea september `19,"'1924. serial ne. l738,587.

This invention, relates to spiders such as are used for supportin the mandrel of an vextl'udingor tube mac e, such machines being usedv in the rubber art, for example,

.' l for extruding a massof plastic rubber comound in the form of a tube, the stock being orced through a delivery die which surrounds the freely projectingend of a mandrel havingv its base or inner end secured to the spider or web mounted within the machine.

The great pressure exerted upon the stock by the feed-screw, to' force thestock through the spider and through the annular-passage defined by the die and mandrel, re-

qulres that the spiders hub, to which the mandrel is attached, be provided with radial arms or web elements of considerable size in cross-section, to provide the necessary strength for supporting the mandrel accurately in posit' flowing stoc b the'radial arms of the spider, in such mac es as have been used prior to our invention, has frequently resulted in the production of a tube of *non-uniform wall-thickness, 'particularly in the case of l ahigh grade stock, aving such life or resilience as apprecia ly to swell transversel of the tube -wall vas it emerges from the ie, the shielding effect ofthe radial spider larms apparently resulting in regions of comparatively low compression in the viscous stock, or zones in which the grain of the stockv is peculiarly distorted. vSaid zones apparently extend from each spider arm to the dies delivery aperture, the latter pref-l erably being not far from the spider, in order that the mandrel 'may be of such short length as notv to rbe bent or -misaligned by 40 the great pressure of the stock. The effect described 1s especially objectionable in the case of thin-walled tubes, where variations of thickness may result in extremely thin zones such as greatly to weaken the product.

5 Various expedients have been proposed for avoiding the result described, but all of .those prior to our invention, so far as we are aware, have had inherent defects. When the spider is dispensed with and the mandrel is secured to the feed-screw, vfor example, andV rotates therewith, objectionable gyration of the delivery end of the mandrel is diliicult to avoid. When the 1on.- The separation of the-- mandrel is mounted in an axial bore formed 1n the feed-screw, and held lstationary by 55 attachment to theA ,feed cylinder, in order to dispense with the spider, iiow of stock into the bore of the screw, about thel mandrel, and consequent binding, is diliicult to avoid.

The chief object ofour invention is to 00 l provide a simple and at the same time efyf'ective type of spider for holding the mandrel in position without resulting in objectionable variation of wall-thickness in the product, and a further and more Specic object is to vprovide suchan improved spider adapted for use in production of thin Walled, readily collapsible tubes, whereby in conjunction with uniformity of wall' thickness, the adhesion of the inner walls 'of the tube may be avoided, as by discharging a blast of powdered soapstone into the tube as it is formed.

' In attainment of these objects we have found that the variations of pressure or structure in each segmental zone of stock passing through the aperture between adjacent spider arms may be compensated by overlaying upon such zone and the one adjacent thereto, in mismatchedl relation, another f' zone ofstock having complementary variations, this effect being obtainable by the provision of an outer series of apertures through the spider, properly mismatched with an inner series of, apertures. 35

Of the accompanying drawings: l

Fig. 1 is -a vertical, longitudinal section of the delivery end portion of a tube ma-A chine embodying our invention. L Fig. 2 is a section on line 2-2 1, our improved mandrel-holding spider be- 'ing shown in elevation and broken away to show its internal structure. l

Referring to the drawings, 10 is the cylinder, 11 the lfeed-screw', 12 the head, 13 95 the die-holding. bushing, and 14 the dieof a tube machine adapted -for extruding rub-- ber tubes and provided with the `usual steam-passagesy 15, 15 4 for keeping the stock warm` and plastic. The' mandrel, 16, is 100 mounted upon our improved' die-holding spider 17.

Said spider comprises a hub 18, into which the rear end of the mandrel 'is screwed, a set of 'spider arms or webs 19, 105 19, here shown as four, radiating from said of Fig.' 90

hub, a web vring connecting the outer `ends ofl said arms, a second set of arms 21,

21, circumferentially offset or staggered with relation to those of the first set, and radiating from said ring, and a relatively heavy outer ring 22 connecting the/ outer ends of the arms 21, and centered by set screws 23, 23 and an axially apertured plug 23a threaded through the head 12, said hub arms and rings defining an inner series of passages 24, 24, and an outer set of passages 25, 25, the passages of each series overlapping those of the other, circumferentially of the machine.

, The spider 17 is preferably formed of strong metal such as vanadium steel, in order that the arms 19 and 21 and the ring 20 may have sutlicient stre'ngth without eX,

cessive size, and said arms and ring are thinned toward their edges, fore and aft, as shown, in order to permit a smooth and substantially stream-line, flow of stock.

It is important that the inner passages 24 and the outer passages' 25 be so proportioned and relatively positioned as to cause the variations in the characteristics or condition of the stock passing lthrough the outer series of passages to compensate those of the stock passing through the inner passages, and we find that this may be simply and easily accomplished by forming the spider with two concentric series of pasv sages of equal radial width and with the outer set of radial arms in evenly spaced alternation with those of the inner set. We do not wholly limit'our claims, however, to only two such series of passages. It will be seen that the several sections of stock, lpassing through the respective apertures,

will/flow together in imbricated relation as 'they pass to the delivery aperture of the die,

providing a laminating effect.

In order to prevent adhesion of the inner walls of the rubber tube in case it collapses or is collapsed before vulcanization, the spider is formed with a soapstone passage or conduit 26, communicating at its outer` end with the axial bore 27 of the plug 23a,

. said passage 26 extending longitudinally in one of the outer set of radial arms 21, circumferentially in the ring 20 to an adjacent radial arm 19 of the inner set, andlongitudinally in the latter to a recess 28 in the spiders hub 18, said recess communicating with an axial bore 29 formed in the mandrel 16, and the plug 2. a being adapted tobe connected with a suitable device .for

the outer radial reach thereof from the outer periphery of the spider, drilling a radial hole at 30, Fig. 2, through the outer tion without departure from its scope, and

we do not wholly limit our claims to the specic construction shown.

' We claim 1. A tube machine comprising a die, means for forcing plastic material through said die, a mandrel, and means for holding said mandrel within said die, said mandrel holding means comprising a spider having web portions defining a plurality of annular series of stock passages, theinner and outer walls of said passages being of concentric, arcuate form, and the passages of the respective series-being of such relative radial width and so disposed in alternate relation circumferentially of the spider as substantially to neutralize the effect of-the` radial web portions upon the wall-thickness of the extruded tube.

2. A tube machine comprising a die, means for forcing plastic material through said die, a mandrel, and means for holding said mandrel within said die, said mandrel holding means comprising a spider having web portions defining two concentric, annu- 'lar series of segment-shaped stock passages,

the passages of one seriesbeing of substantially the same radial Width as those of the' other series, and each passage of one series' being symmetrically disposed with relation to a radial, axial plane passing substantially midway between adjacent passages of the other series.

3. A tube machine comprising a die, means for forcing plastic material through said die, an apertured mandrel, and means for holding said mandrel within said die,

said mandrel holding means comprising a v spider having web portions defining an inner and an outer annular series of stock passages, the passages of each series being circumferentially offset with relation to those of the other, and a web portion of said spider being formed with a conduit leading from a part of the spider radially outside of said annular series of stock passages to a part thereof radially within said series.

4. A tube machine comprising a die, means for forcing plastic material through said die, an apertured mandrel, and means for holding said mandrel within said die,

said mandrel holding means vcomprising a'y spider having a hub portion constituting a support for the mandrel, a set of arms eX- tending outwardly from said hub, an an- 1,603,825' l Y l n Y a nular web-connecting the'outer ends of said vlar web, and then'longntudimully in an armi larms, and aA slecond'sei: of arms extending of the otherxset.

,outwardly from said annular web and cir- In wxtness whereof we huve hereunto I v l flrstI set, vsaid-spider bein formed with a 1924. f v conduit extendingjongitu ally in v`an arm r -ELIAS' E. DAVIDSON. i o f .one s'et,'fhen longitudinally in said annuf.. FLORENZ P. HARTUNG.

' cumferentially-eset' from the arms of the A our hands this 16th.*v day of September,' 

